Overview and Summary of Significant Accounting Policies - Relationship with Former Parent and Related Entities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018
Trinity Industries, Inc.
Related Party Transaction [Line Items]
Sales to Trinity businesses	$ 32.6	$ 76.1
Purchases from Trinity businesses	12.0	24.8
Corporate Segment
Related Party Transaction [Line Items]
Corporate overhead costs	$ 7.9	$ 15.6

Indirect cost incurred related to good produced and service rendered.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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Direct costs arising from transactions with related parties who are not affiliates or joint Ventures. These costs are categorized as cost of goods sold.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
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